Hi. I would like to add an electric heater in my garage for supplemental heat. I am looking at a Dayton unit that hangs from the ceiling because I dont have any wall space for a wall type unit. The Dayton heater requires a 30 amp breaker, but I only have room left for one single pole breaker in my panel. Am I going to have to add a sub panel? Is there any way to consolidate some of the other 15 amp breakers to make room for the 30 amp? Any advise is welcome. Thanks.

A lot of panels have replacement breakers that are duals-- one breaker slot serves two circuits. Using a couple of these will allow you to open up a place for a new 30A breaker without having to put in a sub panel.

Assuming it is a 220v and your breaker box does not accept duel breakers(most older ones don't). . Just go through all your breakers and determine what the load is for each. .. For example most houes do not need a seperate breaker for there dining room and foyer... you can connect 2 wires to a breaker but if it doesnt reach you can make a junction box next to the breaker box.. if you have central air you can create a junction box and steal from that as long as the breaker is between 30 and 40 amps.. this probably isnt an accepted thing to do but who uses an a/c and heater at the same time.

Thanks for the replies everyone. Sorry I was not clear on the 30 amp breaker part, it is a 220 unit so I need 2 spaces instead of one. Thanks CraigFL for the idea about the dual breakers, that would free up the extra space I need. A guy at work ( definetly not an electrician ) said I should add up all the breaker values in my panel and if that exceeds the service amount then I would need another panel. Any truth to that? Thanks again!

Thats not true. Generally panels are designed to handle as many breakersas it has slots. 100amp breaker panels have set amount of slots 200amp would have more. You can figure out a live load too see if you exceed your service load. That is what you are actually using and not what the maximum is before the breaker kicks..

You may want to recognize that some items are required by code to be on a dedicated circuit (i.e.-stove, frig, washer, dryer, sump pump, etc...). From there, you will be able to determine how many open slots you can create.
While your considering the draw on each circuit, you may also want to load balancing the box.

A lot of panels have replacement breakers that are duals-- one breaker slot serves two circuits. Using a couple of these will allow you to open up a place for a new 30A breaker without having to put in a sub panel.

Thanks again for the replies.

Do the dual breakers have the same circuit protection as the singles?

Is there a general rule of thumb as to how many loads ( lights, plugs , tv, etc.. ) can be on a general lighting 15 amp breaker?

If your panel was manufactured in the last 30 years you can get a peanut or tandem breaker for it. All you do is remove 2 breakers that are same size, like single pull 20's or 15's, and replace with peanut. This opens up one spot wich is all you need, cause you already said one was open? Good luck, and if you are not an electrician, always turn off main breaker before working in panels or with power at all....and you probably should have somebody around to watch ya.